1. Field of the Invention
This invention pertains to land vehicles generally, and more specifically to trailing vehicles configured for optimum performance with occupant-propelled wheeled vehicles such as bicycles and the like. Most specifically, the most preferred embodiment of the invention illustrates an aerodynamic, light-weight and safe two-passenger trailer for a bicycle.
2. Description of the Related Art
Bicycles, by their very nature and design, provide an efficient, light-weight and low-cost means of rapid transportation for humans. Bicycle pedals are acted upon by a rider using some of the strongest muscles in the human body. These muscles are well-adapted to provide many repetitions of driving force, while the chain and sprockets typically found in a bicycle enable the rider to provide an optimum combination of force and repetition rate. Wheels with bearings enable the rider to coast without exertion, and thereby derive full benefit from inertia, gravity, tail winds, and the like. Bicycles are most commonly provided with two in-line wheels and a frame extending therebetween, making the bicycle relatively long and tall, but also very narrow. Consequently, a bicycle requires minimal space for storage when not in use, and the bicycle will also present almost no aerodynamic drag when in use.
Aerodynamic drag is a function of the square of the relative velocity between the bicycle and surrounding air, and the coefficient of drag is representative of the aerodynamic efficiency of surfaces which interact with the air during motion. With a bicycle and rider, the vast majority of drag comes from the rider""s own body interacting with the surrounding air. Unfortunately, at even moderate speeds the interaction with air consumes the majority of power provided by the bicycle rider. Consequently, it is highly desirable to not add additional loads to the bicycle rider, since these loads can very adversely impact the speeds and advantages normally attained with a bicycle.
Owing to its narrow stature, there is very limited space available on a bicycle for carrying cargo. Cargo must usually be carried by backpack, bicycle packs including tire, basket or other similar packs and baskets, each which either are extremely limited in cargo capacity or which tend to add a great deal of bulk and air resistance to a bicycle. Furthermore, there is no space available for the safe transport of additional passengers. Bicycle seats for additional passengers tend to be very high and unbalanced, which can undesirably lead to serious accidents or injuries.
As an alternative to supporting cargo and additional persons upon the bicycle, trailers have been designed for attachment to the bicycle that may be towed behind the bicycle. These trailers offer a number of distinct advantages over bicycle mounted carriers, and may include a low center of gravity, a separate wheel support, xe2x80x9cdraftingxe2x80x9d behind the cyclist to take advantage of the airstream about the cyclist, easy separation from the bicycle when not required, and flexibility regarding the size or shape of cargo and passengers. In some cases, the trailer may further be designed for particular stability or ruggedness not inherent in the design of a bicycle.
Undesirably, and as aforementioned, there is only limited power available from a cyclist. This power is very precious and is desirably conserved for transportation in order to make the ride as pleasant and enjoyable as possible. The power is not preferred for dragging an additional load.
Exemplary of the trailers designed for use with bicycles are U.S. Pat. No. 5,641,173 to Cobb, Verd Jr. and also Des. 3470,429 to Smith. In the Cobb patent, an aerodynamically designed trailer has a trailer tongue coupling forward through a universal joint to a bicycle seat post and a single wheel aft of a cargo carrier. The cargo carrier has a vertically extending aerodynamic design which is adaptable to carry either a single child in a seat, a clothes bar that might be used to hang various clothing or garment bags and the like, or a cargo shelf for supporting other diverse cargo. Unfortunately, while the Cobb patent may serve the purpose of carrying clothes or other narrow cargo, the Cobb design is a relatively tall and narrow configuration similar to the bicycle. This design gains little additional space over that already available, for example from a bag hanging from the top bar between seat post and handle bars. Furthermore, the Cobb design attaches at the sea post, which is very high on the bicycle, and includes only a single wheel for the trailer. While this design may suffice when used with ordinary durable cargo, the design is not adequate for those applications where the trailer is used to transport fragile or precious cargo or persons. This is due to the fact that, should the cyclist unexpectedly tip the bicycle, there is nothing to uncouple the carrier from the bicycle or support it independently. Consequently, a child being carried in the trailer will also be dropped to the ground in a violent manner when the cyclist goes down, which is highly undesirable. Should the cyclist leave the bicycle unattended even briefly, motion within the trailer may readily topple both the bicycle and the trailer. Furthermore, the Cobb trailer will only carry a single child, and even then in a backward position, which can be very disorienting and unsettling to some children.
The Smith design represents a much more common configuration for a bicycle trailer, but likewise serves to illustrate the difficult trade-offs that are made in the prior art trailers designed for bicycles. In the Smith patent, the carrier is illustrated having a transparent cover, a wide seat which might accommodate two smaller children in a side-by-side arrangement or one larger child, and a wide and stable wheel base. The lower center of gravity and wider wheel base serve to protect the child or children in the trailer, even if the cyclist or bicycle should topple, since the wide wheel base will be relatively difficult to topple. Unfortunately, the wide wheel base also presents a much larger front surface for interacting with the air, and a greater coefficient of drag. Drag is proportional to the drag coefficient, frontal area and the square of vehicle speed. With a larger front surface and coefficient of drag, the drag is much greater. Unfortunately, the trailer adds a great burden onto the cyclist, preventing a cyclist with the trailers of this design from keeping pace with bicycles without trailers. What is desired then is a trailer capable of transporting more than one child, while protecting the child and still preserving low weight and aerodynamic efficiency.
In a first manifestation, the invention is a trailer which is aerodynamically efficient when towed behind a land vehicle. A carriage within which cargo including persons may be transported has a front, a back spaced from the front, and sides extending from front to back and forming a space for cargo. A shield interposed between carriage and land vehicle protects cargo from hazards during transit. The shield has a convex shape with an apex and a base, the apex displaced from base in a direction parallel to the direction of travel and towards the land vehicle. A tail member has a convex shape with a base adjacent the carriage and an apex displaced from the base in a direction away from the land vehicle. A wheel set moves and maintains the carriage, shield and tail member spaced from the ground. A tongue maintains the trailer spaced a predictable distance from the land vehicle.
In a second manifestation, the invention is a means for transporting cargo aerodynamically behind a bicycle propelled by a cyclist. A means is provided for supporting and enclosing cargo and has a main cargo space, a leading apex, a leading convex surface between the main cargo space and leading apex, a trailing apex, a trailing convex surface between the main cargo space and the trailing apex, and an aerodynamic transition between the leading and trailing apex. A means transmits light reflected from enclosed cargo to cyclist. Another means separates the enclosing means from a surface upon which bicycle and cargo transporting means travel. A means also couples bicycle to enclosing means.
In a third manifestation, the invention is a bicycle trailer. A polyhedral passenger compartment which is generally elliptical in cross-section is taller than wide and has a rigid plastic floor, flaccid side walls, and a generally elliptical frame support about which the passenger compartment is formed. A transparent, convex shield is provided at one end of the polyhedral passenger compartment and a flaccid convex tail cover is provided at a second end of the polyhedral passenger compartment opposite the transparent shield. First and second seats that are in line with each other are located within the passenger compartment. These seats are convertible between passenger seating and cargo supporting. First and second wheels and a frame for supporting the polyhedral passenger compartment are displaced from the ground, the first wheel defining a first plane through which a surface of the first wheel surface rotates and second wheel defining a second plane through which a surface of the second wheel rotates, the first and second planes which are not parallel with each other.
A first object of the invention is to provide a stable, safe and secure means for a cyclist to transport children. A second object of the invention is to enable the cyclist to carry either cargo, one child with cargo, or two children in a stable, safe and secure manner. A third object of the invention is to provide a stable support base which prevents toppling, and a coupling to a bicycle or other land vehicle which uncouples rotation or tipping of the towing vehicle from the trailer. Another object of the invention is to provide sight windows to enable the cyclist to observe the status of the cargo and allow animate cargo to view their surroundings during transit. A further object is to enable the cyclist to transport cargo and children without sacrificing efficiency during transport. Yet another object of the invention is to enable children to enjoy riding in the trailer, regardless of weather conditions. A further object of the invention is to provide for small amenities that help to ensure the safety of the children while also making the ride more pleasurable. These and other objects of the invention are achieved in the preferred embodiment of the invention, which will best understood when considered in association with the appended drawing figures.